Compare the structural features of epithelial and connective tissue. Difference between epithelial tissue and connective tissue

The human body is a certain integral system capable of regulating itself independently and periodically recovering if necessary. This system, in turn, is represented by a large cell set.

At the cellular level, very important processes are carried out in the human body, which include metabolism, reproduction, and so on. In turn, all cells of the human body and other non-cellular structures are grouped into organs, organ systems, tissues, and then into a full-fledged organism.

A tissue is the union of all cells located in human body and non-cellular substances similar to each other in their functions, appearance, education.

Epithelial tissue, better known as epithelium, refers to the tissue that forms the basis of the surface skin, serous membrane, cornea eyeball, digestive, genitourinary and respiratory systems, genitals, it also participates in the formation of glands.

This tissue is characterized by a regenerative feature. Numerous types of epithelium differ in their appearance. The fabric can be:

• Multilayer.
• Equipped with a stratum corneum.
• Single layer, provided with villi (renal, coelomic, intestinal epithelium).

Such tissue is a borderline substance, which implies its direct participation in a number of vital processes:

1. Through the epithelium, gas exchange occurs in the alveoli of the lungs.
2. The process of urine excretion occurs from the renal epithelium.
3. Nutrients are absorbed into the lymph and blood from the intestinal lumen.

The epithelium in the human body performs the most important function - protection, it, in turn, is aimed at protecting the underlying tissues and organs from various kinds of damage. In the human body, a huge number of glands are created from a similar basis.

Epithelial tissue is formed from:

• Ectoderm (covering the cornea of \u200b\u200bthe eye, oral cavity, esophagus, skin).
• Endoderm (gastrointestinal tract).
• Mesoderm (organs genitourinary system, mesothelium).

The formation of epithelial tissue occurs at the initial stage of embryo formation. The epithelium, which is part of the placenta, is directly involved in the exchange essential substances between a fetus and a pregnant woman.

Depending on the origin, epithelial tissue is subdivided into:

• Skin.
• Intestinal.
• Renal.
• Ependymoglial epithelium.
• Coelomic epithelium.

These types of epithelial tissue are characterized by the following features:

1. Epithelial cells are presented in the form of a continuous layer located on the basement membrane. Through this membrane, the epithelial tissue is saturated, which does not contain blood vessels.
2. The epithelium is known for its restorative properties, the integrity of the damaged layer after a certain time interval is fully regenerated.
3. The cellular basis of the tissue has its own structure polarity. It is associated with the apical and basal parts of the cell body.

Within an entire layer between adjacent cells, a connection is formed quite often using desmos... Desmos are numerous structures of very small sizes, they consist of two halves, each of them in the form of a thickening superimposed on the adjacent surface of neighboring cells.

Epithelial tissue has a coating in the form of a plasma membrane containing organelles in the cytoplasm.

Connective tissue is presented in the form of immobile cells, called:

• Fibrocytes.
• Fibroblasts.

Also, this type of tissue contains a large number of free cells (wandering, obese, fat, and so on). Connective tissue aims to shape the human body, as well as resilience and strength. This view tissue also connects organs.

Connective tissue is subdivided into:

• Embryonic - is formed in the womb. This fabric is formed blood cells, muscle structure and so on.
• Reticular - consists of reticulocyte cells that accumulate water in the body. The tissue is involved in the formation of antibodies, this is facilitated by its content in the organs of the lymphatic system.
• Interstitial - the supporting tissue of organs, it fills the gaps between the internal organs in the human body.
• Elastic - is located in tendons and fascia, contains a huge amount of collagen fibers.
• Fatty - is aimed at protecting the body from heat loss.

Connective tissue is represented in the human body in the form of cartilage and bone tissue that make up the human body.

The difference between epithelial tissue and connective tissue:

1. Epithelial tissue covers organs and protects them from external influences, while connective tissue connects organs, transports nutrients between them, and so on.
2. Have connective tissue the intercellular substance is more pronounced.
3. Connective tissue is presented in 4 types: fibrous, gel-like, hard and liquid, epithelial in the 1st layer.
4. Epithelial cells resemble cells in appearance; in connective tissue they have an elongated shape.

Question 1. What tissue does the skin, walls of the mouth, ear and nasal cartilage consist of?

The skin, the walls of the oral cavity are composed of epithelial tissue, and the ear and nasal cartilages are composed of connective tissue.

Questions after the paragraph

Question 1. What is called a cloth?

Groups of cells and intercellular substance that have a similar structure and origin and perform common functions are called tissues.

Question 2. What kind of fabrics do you know? Draw up and fill in the “Fabric variety” chart.

In the body of animals and humans, there are four main groups of tissues: epithelial, connective, muscle and nervous. In muscles, for example, muscle tissue predominates, but connective tissue and nerve tissue are found along with it. The tissue can consist of both the same and different cells.

Question 3. How are connective tissues different from epithelial ones?

The connective tissue contains cells capable of fighting microorganisms, and in case of damage to the main tissue of any organ, this tissue is able to replace the lost elements. So, the scars formed after wounds consist of connective tissue. True, it cannot perform the functions of the tissue that the connective tissue has replaced.

Question 4. What types of epithelial and connective tissue do you know?

Types of epithelial tissue: squamous epithelium, cubic epithelium, ciliated epithelium, columnar epithelium.

Connective tissues include supporting tissues - cartilaginous and bone; liquid tissues - blood and lymph, loose fibrous tissuefilling the space between the organs, accompanying the vessels and nerves; adipose tissue; dense fibrous tissue that is part of the tendons and ligaments.

Question 5. What properties do muscle tissue cells have - smooth, skeletal, cardiac?

The general properties of all muscle tissues are excitability and contractility. Muscle tissue contracts in response to irritation. Thanks to reduction, all human movements and work are carried out internal organs.

Question 6. What functions do neuroglial cells perform?

Neuroglial cells perform in relation to them serving functions: protective and supporting, nutritional and electrically insulating.

Question 7. What is the structure and properties of neurons?

A neuron consists of a body and processes. The body of a neuron contains the nucleus and the main cellular organelles. Neuron processes differ in structure, shape, and function.

Question 8. Compare dendrites and axons. What are their similarities and what are the fundamental differences?

A dendrite is a process that transmits excitation to the body of a neuron. Most often, a neuron has several short branched dendrites. However, there are neurons that have only one long dendrite.

An axon is a long process that transfers information from the body of a neuron to the next neuron or to a working organ. Each neuron has only one axon. The axon branches only at the end, forming short branches - terminal and.

Question 9. What is a synapse? Tell us about how it works.

The points of contact between individual neurons or between neurons and the cells they control are called synapses.

In the extended end of the axon in special vesicles - vesicles is biologically active substance from the group of neurotransmitters. When the nerve impulse propagating along the axon reaches its end, the bubbles approach the membrane, integrate into it, and the transmitter molecules are thrown into the synaptic cleft. These chemical substances act on the membrane of another cell and in this way transmit information to the next neuron or cell of the controlled organ. The neurotransmitter can activate the next cell, causing excitement in it. However, there are neurotransmitters that lead to the suppression of the next neuron. This process is called inhibition.

Excitation and inhibition are critical processesoccurring in the nervous system. It is due to the balance of these two opposite processes at each moment of time that nerve impulses can arise only in a strictly defined group of nerve cells. Our attention, the ability to concentrate on a certain activity is possible thanks to neurons that cut off excess information. Don't be ours nervous system would be overloaded very quickly and could not work normally.

Tasks

1. Look for scars on the skin of yourself or someone you know. Determine what kind of fabric they are made of. Explain why they do not tan and are different in texture from healthy skin areas.

Scars are made up of connective tissue. These cells lack the pigment melanin, so these areas of skin do not tan in the sun.

2. Look under a microscope at samples of epithelial and connective tissue. Using Figures 16 and 17, tell us about their structure.

The epithelial cell has a thick membrane (a small amount of intercellular substance). The connective tissue has a high ability to regenerate, (the intercellular substance performs the main function.

3. In Figure 20, locate the neuron body, nucleus, dendrites and axon. Determine in which direction the nerve impulses will go along the processes if the cell is excited.

If the cell is excited, then the nerve impulse always moves from the cell body along the axon to the synapses.

4. It is known that breast and abdominal cavity divided by the diaphragm involved in breathing. Does it consist of smooth or striated muscles? Hold your breath, take an arbitrary breath in and out and answer this question.

The diaphragm is made up of muscle tissue. It is composed of smooth muscles.

5. There are many classifications of neurons. Some of them are already known to you. Using additional sources of information, suggest other classifications than those presented in the textbook.

Classification of neurons by the number of processes:

1. Multipolar neurons - neurons with multiple processes

2. Bipolar neurons - have 2 processes

3. Unipolar

a) Pseudo-unipolar (they have 1 process, although initially they are laid as double-processes, but the bases of the processes are very close and it seems like 1 process)

b) True unipolar - 1 process

Epithelial tissue - the outer surface of human skin, as well as the lining surface of the mucous membranes of internal organs, gastrointestinal tract, lungs, most glands.

The epithelium is devoid of blood vessels, so the nourishment comes from the adjacent connective tissues, which are powered by the bloodstream.

Functions of epithelial tissue

Main function skin epithelial tissue - protective, that is, limiting exposure external factors on the internal organs. Epithelial tissue has a multilayer structure, so keratinized (dead) cells are quickly replaced by new ones. It is known that epithelial tissue has increased regenerative properties, which is why human skin is rapidly renewed.

There is also an intestinal epithelial tissue with a single layer structure, which has absorptive properties, due to which digestion occurs. In addition, the intestinal epithelium tends to release chemicals such as sulfuric acid.

Human epithelial tissue covers almost all organs from the cornea of \u200b\u200bthe eye to the respiratory and genitourinary system. Some types of epithelial tissue are involved in protein and gas metabolism.

The structure of epithelial tissue

Monolayer epithelial cells are located on the basement membrane and form one layer with it. The cells of stratified epithelium are formed from several layers and only the lowest layer is the basement membrane.

According to the shape of the structure, epithelial tissue is: cubic, flat, cylindrical, ciliated, transitional, glandular, etc.

Glandular epithelial tissue possesses secretory functions, that is, the ability to allocate a secret. The glandular epithelium is located in the intestine, makes up sweat and salivary glands, glands internal secretion etc.

The role of epithelial tissue in the human body

The epithelium plays a barrier role, protecting internal tissues and also aids in the absorption of nutrients. When eating hot food, part of the intestinal epithelium dies off and is completely restored overnight.

Connective tissue

Connective tissue - building matter that unites and fills the entire body.

Connective tissue is present in nature in several states at once: liquid, gel, solid and fibrous.

Accordingly, a distinction is made between blood and lymph, fat and cartilage, bones, ligaments and tendons, as well as various intermediate body fluids. The peculiarity of connective tissue is that there is much more intercellular substance in it than the cells themselves.

Types of connective tissue

— Cartilaginous, there are three types:
a) Hyaline cartilage;
b) Elastic;
c) Fibrous.

— Bone (consists of forming cells - osteoblast, and destructive ones - osteoclast);

— Fibrous, in turn happens:
a) Loose (creates a frame for organs);
b) Formulated dense (forms tendons and ligaments);
c) Unformed dense (the perichondrium and periosteum are built from it).

— Trophic (blood and lymph);

— Specialized:
a) Reticular (tonsils, bone marrow are formed from it, the lymph nodes, kidneys and liver);
b) Fat (subcutaneous energy reservoir, heat regulator);
c) Pigmented (iris, nipple halo, anus circumference);
d) Intermediate (synovial, cerebrospinal and other auxiliary fluids).

Connective tissue functions

These structural features allow the connective tissue to perform various functions:

1. Mechanical (supporting) function is performed by bone and cartilaginous tissues, as well as fibrous connective tissue of tendons;
2. Protective the function is performed by adipose tissue;
3. Transportthe function is performed by liquid connective tissues: blood and lymph.

Blood provides the transport of oxygen and carbon dioxide, nutrients, metabolic products. Thus, connective tissue connects body parts to each other.

Connective tissue structure

Most of the connective tissue is the intercellular matrix of collagen and non-collagen proteins.

Besides him - naturally cells, as well as a number of fibrous structures. The most important cells can be called fibroblasts that produce substances of the intercellular fluid (elastin, collagen, etc.).

Basophils (immune function), macrophages (destroyers of pathogens) and melanocytes (responsible for pigmentation) are also important in the structure.

Cells make up all tissues, tissues make up organs, organs, systems and systems make up organisms. Cells are of different types that make up different tissues. Each has different characteristics, but the epithelium and connective tissue usually mix with each other. To distinguish the differences between them, detailed explanations and descriptions are provided below.

Epithelial tissue

Common sense tells us that epithelial cells make up epithelial tissues. They are located in one or more layers. These include the inner and outer lining of body cavities such as skin, lungs, kidneys, mucous membranes, and so on. These cells are very close to each other and have a very small matrix among them. There are tight junctions between cells that regulate the passage of substances. These tissues do not have blood vessels or capillaries, but they get their nutrients from the lower thin sheet of connective tissue known as the basement membrane.

∙ Types of epithelial tissue

Connective tissue

Connective tissue is composed of fibers that form a network and a semi-fluid intracellular matrix. It is there that the blood vessels and nerves. It is responsible for the distribution of nutrients and oxygen to all tissues. It forms the skeleton, nerves, fat, blood, and muscle. It functions not only to support and protect, but also to bind other tissues that promote communication and transport. Besides adipose tissue, one type of connective tissue is responsible for providing heat to the body. Connective tissues are a vital and significant component of almost all organs in the body.

∙ Types of connective tissue

Epithelial and connective tissue

Epithelial tissue and connective tissue differ in different ways, but both work in conjunction with each other and among other tissue types. It is incredible that the body is composed of them, which makes all systems in the best... Examining the human body has made us realize how amazing it is and we need to support it by taking care of our well-being and staying healthy.

Epithelial tissue, or epithelium, covers the outside of the body, lines the body cavities and internal organs, and also forms most of the glands.

Varieties of the epithelium have significant structural variations, depending on the origin (epithelial tissue develops from all three germ layers) of the epithelium and its functions.

However, all species have common features that characterize epithelial tissue:

1. The epithelium is a layer of cells, due to which it can protect the underlying tissues from external influences and exchange between the external and internal environment; violation of the integrity of the reservoir leads to a weakening of its protective properties, to the possibility of infection.
2. It is located on the connective tissue (basement membrane), from which nutrients are supplied to it.
3. Epithelial cells are polarized, i.e. parts of the cell (basal), lying closer to the basement membrane, have one structure, and the opposite part of the cell (apical) has another; different components of the cell are located in each part.
4. Possesses a high ability to regenerate (restore). Epithelial tissue contains no intercellular substance or contains very little of it.

Epithelial tissue formation

Epithelial tissue is made up of epithelial cells, which are tightly connected to each other and form a continuous layer.

Epithelial cells are always found on the basement membrane. It delimits them from the loose connective tissue that lies below, performing a barrier function, and prevents the germination of the epithelium.

The basement membrane plays an important role in the trophism of epithelial tissue. Since the epithelium is devoid of vessels, it receives nutrition through the basement membrane from the vessels of the connective tissue.

Classification by origin

Depending on the origin, the epithelium is divided into six types, each of which occupies a certain place in the body.

1. Cutaneous - develops from the ectoderm, localized in the oral cavity, esophagus, cornea, and so on.
2. Intestinal - develops from the endoderm, lines the stomach, the small intestine and the large intestine
3. Coelomic - develops from the ventral mesoderm, forms serous membranes.
4. Ependymoglial - develops from the neural tube, lines the brain cavity.
5. Angiodermal - develops from the mesenchyme (also called the endothelium), lining the blood and lymph vessels.
6. Renal - develops from the intermediate mesoderm, occurs in the renal tubules.

Features of the structure of epithelial tissue

According to the shape and function of the cells, the epithelium is divided into flat, cubic, cylindrical (prismatic), ciliated (ciliated), as well as single-layer, consisting of one layer of cells, and multilayer, consisting of several layers.

Single layer

Single layer flat the epithelium is formed by a thin layer of cells with uneven edges, the surface of which is covered with microvilli. There are mononuclear cells, as well as with two or three nuclei.

Single layer cubic consists of cells with the same height and width, characteristic of the glands excretory duct. The single-layer columnar epithelium is divided into three types:

1. Bordered - found in the intestines, gallbladder, possesses adsorbing properties.
2. Ciliated - is characteristic of the oviducts, in the cells of which there are mobile cilia at the apical pole (they contribute to the movement of the egg).
3. Glandular - localized in the stomach, produces a mucous secret.

Single layer multi-row the epithelium lines airways and contains three types of cells: ciliated, intercalated, goblet and endocrine. Together they ensure the normal functioning of the respiratory system, protect against the ingress of foreign particles (for example, the movement of cilia and mucous secretions help to remove dust from the respiratory tract). Endocrine cells produce hormones for local regulation.

Multilayer

Multilayer flat non-keratinizing the epithelium is located in the cornea, anal region of the rectum, etc. There are three layers:

• The basal layer is formed by cells in the form of a cylinder, they divide in a mitotic way, some of the cells belong to the stem;
• spinous layer - cells have processes that penetrate between the apical ends of the cells of the basal layer;
• a layer of flat cells - they are outside, constantly die off and peel off.

Multilayer flat keratinizing the epithelium covers the surface of the skin. There are five different layers:

1. Basal - formed by poorly differentiated stem cells, together with pigment - melanocytes.
2. The spinous layer together with the basal layer form the growth zone of the epidermis.
3. The granular layer is built of flat cells, in the cytoplasm of which the keratoglian protein is located.
4. The shiny layer got its name from its characteristic appearance during microscopic examination of histological preparations. It is a homogeneous shiny strip, which stands out due to the presence of elaidin in flat cells.
5. The stratum corneum consists of horny scales filled with keratin. The scales that are closer to the surface are susceptible to the action of lysosomal enzymes and lose their connection with the underlying cells, therefore they constantly peel off.

Transitional epithelium located in renal tissue, urinary tract, bladder... Has three layers:

• Basal - consists of cells with intense coloration;
• intermediate - with cells of various shapes;
• integumentary - has large cells with two or three nuclei.

It is common for the transitional epithelium to change shape depending on the state of the organ wall; they can flatten or acquire a pear-shaped shape.

Special types of epithelium

Aceto-white -it is an abnormal epithelium that becomes intensely white when exposed to acetic acid. Its appearance during colposcopic examination makes it possible to identify the pathological process in the early stages.

Buccal -collected from the inner surface of the cheek, is used for genetic examination and the establishment of family ties.

Functions of epithelial tissue

Located on the surface of the body and organs, the epithelium is a border tissue. This situation determines its protective function: the protection of the underlying tissues from harmful mechanical, chemical and other influences. In addition, through the epithelium occur metabolic processes - absorption or release of various substances.

The epithelium, which is part of the glands, has the ability to form special substances - secrets, and also to release them into the blood and lymph or into the ducts of the glands. This epithelium is called secretory, or glandular.

Differences between loose fibrous connective tissue and epithelial

Epithelial and connective tissue perform different functions: protective and secretory in the epithelium, supporting and transport in connective tissue.

The cells of the epithelial tissue are tightly interconnected, there is practically no intercellular fluid. There is a large amount of intercellular substance in the connective tissue, the cells are not tightly connected to each other.